Accumulator



B. vN. ASHTON May 22, `1956 ACCUMULATOR Filed May l, 1953 A QN .vm mw @N2 Q, om 2 Nm mi: lil /l mw l @TVI NN. S O\ Tm, mm. \N ON United StatesPatent" O ACCUMULATOR Benjamin N. Ashton, Kingston, N. Y., assignor toElectrol Incorporated, Kingston, N. Y., a corporation of Delaware 'lApplication May 1, '1953, serial No. 352,550

s ciaims. (ci. 13s- 31) This invention relates to improvements inaccumulators for hydraulic systems and it relates `particularly to animproved and simplified type of piston-type accumulator suitable for usein aircraft hydraulic systems and in other high or low pressurehydraulic systems.

It has beenproposed heretofore to provide pistontype accumulators whichinclude a metallic cylinder having heads at its opposite ends and havinga piston which is slidable lengthwise of the cylinder and divides itinto a liquid-receiving chamber tobe connected to the hydraulic system'and a gas-receiving chamber to be lled with air or other gas underpressure.'v `In many of these prior accumulators, difliculty isencountered in providing piston rings on the piston which provide asufficiently good seal with the cylinder wall to prevent escape of gasand liquid past the piston and mixing thereof with resultant adverseeffects on the hydraulic system.

In my Patent No. 2,440,065, dated April 20, 1948, and in my co-pendingapplication Serial No. 337,553, filed February 18, 1953, I havedisclosed several forms of sealing means which eliminate leakage of thegas and hydraulic liquid past the seals between the piston and thecylinder and mixing of them in the gas or liquid chambers of theaccumulator. This desirable result is achieved by using resilientsealing rings or the like on the piston or in the cylinder and providingmeans for maintaining a pressure diierential on opposite sides of therings to thereby cause them to seat tightly against the cylinder and thepiston to preclude leakage therebetween.

Even with my prior types of accumulators, the manufacture of thecylinder and the pistons and the provision of suitable cylinder headsand sealing means therefor produce engineering and production problemsthat render the accumulators more expensive and complex than is to bedesired. Thus, in most of the prior accumulator-s, one or both ends ofthe cylinder have removable heads to permit access to the interior ofthe cylinder. Such removable heads require seals or packings therein toprevent escape of liquid and/or gas and, in some in stances, a safetymechanism has been provided to prevent removal of the cylinder =headwhile the pressure is still present in the hydraulic system or theaccumulator.

`I have discovered that the construction of the accumulator can begreatly simplied and that the accumulator cylinder can be reduced incomplexity so that it can be manufactured more readily and at lowercost. Such a cylinder can be provided with seals of the resilient ringtype for cooperation with the piston in the cylinder, these rings beingso located with respect to the cylinder that they are inherentlysubjected to different pressures on their opposite sides to obtain thesealing action referred to above.

For a better understanding of the present invention reference may be hadto the accompanying drawing in which the single ligure is a View inlongitudinal section through a typical accumulator embodying the presentinvention.

or sleeve 13 having piston` heads 14 `and 1,5 welded in its oppositeends. kIf desired, one or the other of the piston heads 14 and 15 may beomitted. i i

The tubular skirt 13 can be'formed of polished but not necessarilyprecision honed tubing, such as stainless steel tubing or the like andititsi slidably within the cylinder 11 for free movement therealong. The`piston 12 does `not have to t the'cylinder 11 withinclose tolerancesbut their contacting surfaces should be smooth so that the piston movesfreely in the `cylinder `without excessive radial play. i

The cylinder 11 of the accumulator is of -novel `con-y struction. Itconsists of two-opposed hollow cup like sections 16 and 17 which are of'circular 'crosssection and generally `cylindrical shape, The cylindersection 16 has a head 18 `atits outer end which is in' tegral with itand is provided with a passage 19 inlwhich may be mounted an air checkvalve or `the lil ;e;thr ough which air or other` gas -under pressure islintroduced into the accumulator to the leftjof `the piston 12. f'l`hc.cylinder section 16 has a thickened portion 20,-at .its right-hand endprovided `with external threads 21.V

The cylinder section 17 isv similar to the sectionl` i in that it alsohas a cylinder head 22 yatV itsrghtThand end provided with a` passageand coupling` `23 enabling it to be connected to the hydraulicsystem;..The lefthand end of the cylinder section 17 also has a` thickenedportion 24 having a tubular extension 25 provided with internal threads26 which are screwed on to the threads 21 of the section 16 to connectthe cylinder sections in end-to-end relation, as shown in the drawing. v

The thickened portions 20 and 24 of the cylinder sections have internalcircumferential grooves 27, 28, respectively, therein. The grooves 27and 2S receive resilient sealing membersgsuch as, the O-ring seals 29and 30 which bear against the bottoms of the grooves and the skirt 13 ofthe piston in all positions of the latter axially of the cylinder 11.

It will be apparent that when air or other gas under pressure isadmitted into the cylinder to the left of the piston and the coupling 23is connected to the hydraulic system, the piston will be displacedendwise in the ac cumulator cylinder as the pressures at opposite endsof it vary.

The ring seal 29 will be subjected to the pressure of the air on itsleft-hand side while the ring 30 will be subjected to the pressure ofthe liquid on its right-hand side. In order to provide maximum sealingeffect with `the rings 29 and 30 the pressures on opposite sides of eachof the rings 29 and 30 are kept unequal, as explained in my Patent No.2,440,065. In my new accumulator the threadedy connection between thetwo cylinder sections 16 and 17 provides a suitable means for enablingthe rings 29 and 30 to be subjected to unequal pressures. Thus, if thethreads 21, 26 are not in gas-tight engagement, the space between therings 29 and 30 will be at approximately atmospheric pressure while thepressures on the outer surfaces of the rings may be 1,000 lbs. persquare inch or higher in an aircraft hydraulic system, for example. Aporous packing 31 may be mounted within a groove 32 at the joint 33between the two threaded sleeves to permit air to leave or enter thespace between the rings 21, 26. If the threads are relatively tightttingor in substantially gas-tight relation, a radial bore 33 may be drilledthrough the sleeve 24 to communicate with the groove 32. In any event,the location of the sealing rings 29 and 30 makes it unnecessary to havethe connection between the ends of the sleeves 16 and 17 leakproof. Infact, it is advantageous to have a.

leaky joint between the sleeves 16 and 17 to increase the sealing-eiciency of the rings 29 and 30.

It will be seen that the new accumulator is formed essentiallypof threepieces, not including the two .sealing rings l2,9 and 30'. The pistonand accumulator sections do not have to be machined or honed to aprecision i'it becausethe resilient seal-ing rings 29 andv 30 readilycompensate for irregularities in the surface of the piston. The newaccumulator does not need removable cylinder heads and the packings orseals which are required to maintain rthe heads inleak-tight relation tothe cylinden. It maybe fabricated from tubing or from simple castingswith a minimum ofr finishing and precision operations.

It-willl be understood that the accumulator can be made CFI in varioussizes dependingy upon requirements and that if desired, ahigh pressuresource, such as a small bag type accumulator, can be connected to theradial passage 33- to` enable the accumulator member to be used in lowpressuresystems: as suggested in my co-pending application Serial No.337,553. Therefore, the form of the invention described herein should beconsidered as illustrative and not as limiting the scope of thefollowing claims.

I` claim:

1. An accumulator for hydraulic systems comprising a pair of hollowcylindrical members each having an open end andL an integralcylinderhead at its outer end, means connecting said members with their openends in opposition to form a cylinder having the connecting meanssubstantially at its midportion, an elongated pistonslidable aX-iallytinsaid cylinder and' at all times extending into both ofsaid cylindricalmembers, resilient sealing members interposed between each cylindricalmember and the piston, Vsaid'sealing member being located on oppositesides of said connecting means and engaging said cylinder and saidpiston in all positions of the latter in said cylinder, and a passagefrom the interior of said cylinder between said sealing members to theoutside of said cylinder.

2. An accumulator for hydraulic systems comprising a cylinder, saidcylinder including a pair of hollow cupshaped sections havingcomplementally threaded open inner ends and integral cylinder heads attheir outer ends, said cup-sections being screwed together to form ajoint at about lthe middle of the cylinder and each having a groovetherein adjacent to its open inner end, an elongated piston slidable insaid cylinder, means to admit gas into and discharge it from saidcylinder at said joint and resilient sealing means in each groove ofsaid cup-sections on opposite sides of said jointand in` sealingyengagement with said` piston in all positions of said piston in saidcylinder.

3. The accumulator set forth in claim 2 in which the means to admit anddischarge gas comprises a passage through the wall of' said cylinderbetween said sealing means.

References Cited in the tile of this patent UNITED STATES PATENTS1,590,587' McFarland June 29, 1926 2,360,731 Smith Oct. 17, 19442,411,229 Pratt Nov. 19, 1946 2,411,315 Ashton Nov. 19, 1946 2,437,586Aber Mar. 9, 1948 2,440,065 Ashton Apr. 20, 1948

